Several populous states in India, an under-vaccinated country as it is, are showing a decline in child vaccination rates. Notable among them is Tamil Nadu, where the percentage of children aged up to 23 months to have received full vaccination has dropped from 82% in 2007-08 to 56% in 2012-13.

This alarming fall comes in the backdrop of the introduction in the state government’s immunization programme, in December 2011, of the pentavalent vaccine—a new, more expensive combination that claims to offer additional protection against Hepatitis B and Haemophilus influenza B.

A section of doctors have been contesting the efficacy of, and need for, the pentavalent vaccine, citing post-immunization deaths and the cost-benefit for a developing country like India. As more state governments make the pentavalent vaccine the new standard in their immunization programmes, a conclusive answer has become an imperative.